The Joint Strike Fighter program started with a set of requirements for a tactical fighter that would meet the operational needs of the US Air Force, US Navy, and US Marine Corps using an airframe that maximized the number of common parts and thereby reduce development and maintenance costs. As with any ambitious program like this, the devil is in the details and as the program evolved, challenges arose. The first step in the program was to determine the best overall design and Boeing developed the X-32 that had, shall we say, a rather unique appearance. Lockheed Martin countered with the X-35 and this design would ultimately prevail. This victory made Lockheed Martin the only US company to produce the only two Generation Five fighters in US service – the F-22 Raptor and the F-35 Lightning II.
